1. Technical Field
The present invention relates to a light scanning device and an image formation apparatus.
2. Related Art
For example, as an apparatus which displays a desired image (for example, promotional advertising such as a commercial message) on a screen, an apparatus configured so as to scan the screen in a horizontal direction and a vertical direction with laser light emitted from a light source by using two galvano-mirrors is known (refer to JP-A-2003-131151, for example). Further, in an apparatus described in JP-A-2003-131151, a drive timing of each galvano-mirror is controlled on the basis of a detection signal of an optical sensor fixed on the screen. Further, the maximum displacement angle of the galvano-mirror can also be sought from the detection signal of the optical sensor.
However, in the apparatus described in JP-A-2003-131151, in the case of changing the size of an image on the screen by changing the maximum displacement angle of the galvano-mirror, since the optical sensor is fixed with respect to the screen, according to the magnitude of the maximum displacement angle of the galvano-mirror (particularly, in a case where the maximum displacement angle is “large”), the detection accuracy of the optical sensor tends to be lowered. For example, in a case where the maximum displacement angle is 40 degrees and the optical sensor is installed at a position where it reacts best to the maximum displacement angle, if the maximum displacement angle is changed to 80 degrees, the resolving power of the deflection angle which can be detected by the optical sensor, is lowered. In this manner, in the apparatus described in JP-A-2003-131151, there is a problem in that a difference occurs in the detection accuracy of the maximum displacement angle, so that it is not possible to accurately detect and control turning (oscillation) of the galvano-mirror at the maximum displacement angle.